The initramfs has a reduced set of modules to boot and then
in diskless mode hands over to the 'real' OS for all userspace
to use the more substantial root filesystem with all of the modules.
However one exception is kernel module autoload, which induces modprobe
to run in the initial mount namespace unconditionally.
Thus, preserve the ramfs drivers (just in case) but have the autoloading
pivot
to the normal root filesystem to get the full complement of modules.
